JPS59185071A - Controller of reproducing speed of information recording disc - Google Patents

Abstract

PURPOSE:To obtain a reproducing speed controller requiring no long time for random accessing by providing a means forecasting the number of rotations of a disc at an object position of random access, means controlling the forecast number of revolutions, and a means moving an information reader at the moment or after the said number of revolutions is controlled. CONSTITUTION:An object voltage output circuit 24 consists of plural preset voltage sources and a changeover switch 25. The switch 25 is controlled by a system control circuit 23. The system control circuit 23 incorporates a table and selects an object number of revolutions depending on the absolute time of the random access object position. The voltage in response to the number of revolutions is the preset voltage source and a motor drive voltage giving a value close to the number of revolutions at the object position is applied to a motor 2 by changing over the switch 25. After a voltage producing the objective number of revolutions is set ahead the accessing in this example, the accessing is attained. When the accessing is finished, the mode is changed from the start mode into the steady-state mode and the steady-state number of revolutions is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application) The present invention relates to a reproduction speed control device Cζ for an information recording disc recorded at a constant linear velocity.

(Background) FIG. 1 shows a block diagram of a signal playback speed control method proposed by the present inventors for a digital audio disk (DAD).

In Fig. 1, numeral 1 is a digital audio disc, and in order to increase the recording density, the signal recording speed is constant regardless of the position on the inner or outer circumference of the disc.
V (Conatant Liner Verocit)
y) method is adopted. Therefore, the rotation speed of the motor 2 is changed depending on the read position of the disk.

3 is a synchronization signal detection and reproduction circuit, which detects the synchronization signal contained in the signal read from the disk 1,
This circuit outputs only synchronizing signal pulses. This circuit 3 also has the function of generating a pulse at the position where the synchronizing signal should originally be to supplement the missing synchronizing signal due to the lifting of the disk 1 or the like. Synchronous signal detection regeneration circuit 3
There is a limit to the reproduction range of the synchronization signal generated by the recording modulation method.

This will be explained by taking the modulation method shown in FIG. 2 as an example. The details of the modulation method will be omitted, but in this method, the reference clock frequency is 4. 3 2 1 8 M}Iz), information is recorded using pulses with a width of 3T to IIT. Also, the synchronization signal is 11T.

It is defined as two consecutive patterns of ``H'', ``L'' or ``L'' and ``H'' of 11T, and is recorded every 588T.Therefore, the frequency of the sync signal The sync signal detection and reproducing circuit 3 detects the frequency of the sync signal in the read signal. From 3T.4T,5T,...
...The IOT signal and the IIT signal must be counted and accurately distinguished using a cross signal. L.I.
In order to distinguish between the 10'T and IIT signals, which have pulse widths closest to T, the 11T signal needs to be 105T or more. In other words, the synchronizing signal frequency needs to be within 1, that is, ±45% of the normal frequency ±0.5 wave number. Therefore, when the synchronizing signal frequency is ±45% or more, the synchronizing signal detection and reproducing circuit 3 becomes unable to identify the synchronizing signal and stops signal reproduction.

The explanation will be given by returning to FIG. 1 again. Reference numeral 6 denotes a frequency-voltage converter (hereinafter referred to as an F-V converter), which counts the synchronizing signal frequency and outputs a voltage according to the counted value. The output of the F-V converter 6 is inputted to an error amplifier 8 via a low-pass filter 7, and a voltage corresponding to the difference from a reference voltage 9 is fed back to the motor 2 via a drive amplifier 10. By controlling the rotational speed of the motor, the speed at which signals are read from the disk l is controlled to be constant.

As described above, since the synchronizing signal detection and reproducing circuit 3 does not operate unless the synchronizing signal frequency is within ±4.5% of the normal value, lζ does not output a synchronizing signal at startup. Therefore, until the synchronization signal detection and reproduction circuit 3 starts operating, a pseudo synchronization signal is generated to change the rotation speed of the disk 1 or motor 2 to the normal rotation speed l.
It is necessary to bring it closer to ζ. The pseudo synchronization signal generation circuit 5 plays this role. Further, 4 is a switching device. This switching device 4, as well as the discriminator 11iζ which determines whether or not a synchronization signal has been detected, is switched to the a side during startup and to the b side during normal operation.

The operation of the pseudo synchronization signal generation circuit 5 will be explained below. As already explained, this method is composed of signals with a pulse width of 3T to LIT. And maximum pulse width 11T
(7) “H”, “L” or it “L”.

``t('' Two consecutive patterns are used as the synchronization signal, and the interval between the synchronization signals is 588T. Therefore, even if the synchronization signal cannot be detected, the maximum pulse width can be detected and found, and this interval can be determined by □ By multiplying by 1, the pseudo period of the synchronization signal can be obtained.

The pseudo synchronous signal generating circuit 5 is a concrete example of this, and 12 is a maximum pulse width detector. This maximum pulse width detector 12 counts pulses * with pulses narrower than the interval of at least T, and calculates the maximum pulse width value within a certain time period. 13 is a computing unit that predicts the synchronization signal interval. Reference numeral 14 denotes a pulse generator, which uses the value obtained by the arithmetic unit 13 as a division ratio, divides the pulses obtained by counting the pulse width, and generates a pseudo synchronization signal.

As explained above, no matter where the information reading device that reads the information signal from the disk 1 is located, if the synchronization signal cannot be detected, the pseudo synchronization signal generation circuit 5 generates a pseudo synchronization signal. , the motor 2 can be pulled into steady rotation using the P loop described below.

The loop composed of the symbols 1, 3, 6, 7, 8, and 10°2 described above is called a frequency control loop (hereinafter referred to as P loop), and serves to reduce rotational speed unevenness.

The rotation speed of the motor 2 is determined by the reference voltage 9, but in order to ensure the accuracy and stability of the synchronization signal (in addition to the ζP loop), a phase control loop is provided. , 15, 16, 17, 18° 19.10
．． 2, and serves to match the absolute value of the rotation speed of the motor 2 with the synchronization signal.

This loop is generally called an I-loop.

Next, this loop will be explained. The signal output from the base single frequency oscillator 15 is frequency-divided by the divider 16. The -power and synchronization signals are frequency-divided by the divider 17 so that the frequency is equal to the frequency of the output of the divider 16. It is also input to the phase comparator 18. A voltage corresponding to the phase difference between the two signals is output from the phase comparator 18. The output of the phase comparator 18 is added to P loose via a low-pass filter 19,
Further, the voltage is applied to the motor 2Iζ via the drive amplifier 1o. Therefore, the rotation speed of the motor 2 is fixed to the reference frequency of the reference frequency generator 15.

Further, reference numerals 21 and 22 in FIG. 1 are switching devices. The switching devices 21 and 22 are switched for each rotation mode by a system control circuit 23 consisting of a microcomputer or the like. This switching state is shown in FIG.

When starting the motor 2, a synchronizing signal cannot be obtained, so the switching device 4 switches to contact a on the pseudo synchronizing signal generation circuit side, and the switching device 22 switches to contact C on the output side of the F-V converter 6. Device 21 is switched to contact g. As a result, the IC is configured so that the (1) loop does not cause any disturbance until it is pulled into the synchronization signal detection range.

During normal operation, the switching device 4 is connected to the contact point C, and the switching device 22 is connected to the contact point C.
Then, the switching device 21 is switched to contact e and operates as described above.

Next, random access will be explained.

There is a menu area on the innermost circumference of the disc 1, in which information such as the number of songs and the absolute time at which each side starts (playing time from the innermost circumference) is recorded. The system control circuit 23 stores this information in, for example, RAM1ζ, so when you want to access a desired track number, compare the current absolute time with the absolute time of the destination, and move the reading device according to the difference. can be done. Therefore, quick access is possible.

When moving the reading device that reads information from the disk 1, it is necessary to turn off the trunk servo that follows the signal track, so no signal can be obtained from the disk 1 while it is moving. Therefore, the synchronization signal cannot be obtained, and since the information is incomplete, the pseudo synchronization signal circuit may not operate correctly, and there is a risk that the motor speed control circuit may run out of control.

Therefore, as shown in FIG. 3, at the time of access, the switching circuit 21 connects the contact f connected to the output of the hold circuit 20 in FIG.
Connect. Further, the switching device 22 is connected to the contact point d, and the motor 2 is rotated at a constant speed with no input. Then, in this state, move the reading device, and after moving, start the trunk servo. The motor speed control circuit is then activated.

FIG. 4 shows the relationship between the radius and rotational speed of a digital audio disc. The innermost circumference has a radius of about 25 m and a rotational speed of about 8 rpm, and the outermost circumference has a radius of about 60 m and a rotational speed of 3.3 rps.

If the outermost song is accessed while the innermost song is being played, the motor servo mode is switched as shown in FIG.

That is, the motor rotational speed is held at the rotational speed of the inner circumference, and after the outer circumference is accessed, the motor enters the startup mode and takes time C and T, and then enters the steady mode.

Next, the functions of the system control circuit 23 of this conventional example will be explained with reference to the flowchart of FIG.

Step S1...When entering random access, rule 1
By reading the information contained in the ``h'', it is possible to find out which l1IIth hn access destination is. For example, it can be seen that it is the 6th song.

Generally, when a user enters the number of the song they want to play,
Since the data of that number is temporarily stored in the RAM, it is possible to know which song to access by reading the RAM as described above.

Step S2: The data in the RAM is read to determine the absolute start time of the 6th song. 1
For example, it can be seen that it is 16 minutes oO seconds. This is because the system control circuit reads in advance the various data contained in the innermost circumference of the disk and stores it in the RAM in the system control circuit, so the start time as described above is I understand.

Step S3: The travel time of the reading device (pickup) is calculated based on the target time and the current time. For example, it is determined to be X seconds.

Step S4: Hold the current rotation speed.

Step S5...Turn off the track servo and move the pickup for X seconds. Then turn on the track servo.

Step S6: Read the current jump absolute time of the arrival point from the display. Assume that the value is, for example, 8 minutes per second. Note that this absolute time is stored in the track.

Step S7... It is determined whether 8 minutes seconds is greater than 16 minutes 00 seconds. If it is larger, proceed to step S8,
If it is smaller, proceed to step SIQ.

Step S8: If the error from the target is less than a certain value, the process proceeds to step 12; if no, the process proceeds to step S9.

Step S9...The track servo is turned off again...
The pickup is moved back y seconds. Then, the track servo is turned on. After that, return to step S6, step S6, 87°S8. S9 Ah Louis is step S6. S
7. S10°811 is executed.

Step S10. Step Sll...Steps s8 to S9 are the same, so the explanation will be omitted.

Step S12...The pickup is returned by one trunk.

Step S13...The disc name (current special absolute time) is read.

Step S14: It is determined whether the target time has come. If YES, steady play is started; if NO, the process returns to step S12.

Step S15...The pickup is advanced by one track.

Step 816...The current time is read to disk.

Step S17: It is determined whether the target time has come. If YES, steady performance is started. If NO, the process advances to step S15.

As mentioned above, in the random access of the conventional device, a waiting time T, (see Figure 5) of the motor servo is required. Correct access. This modification is repeated several times, as is clear from the flowchart of FIG. Therefore, there is a drawback that the motor servo waiting time T1 accounts for a large proportion of the total access time.

Furthermore, in order to shorten the access time, there has been a demand for reducing this waiting time T1.

(Objective) An object of the present invention is to provide a playback speed control system that requires a short time for random access.

(Summary) The present invention is characterized by a means for predicting the number of rotations of the disk at a target position of random access in a playback speed control device for a disk in which an information signal and a synchronization signal are recorded;
A random method comprising means for performing predicted rotational speed control, and means for moving an information reading device at the same time as or after performing the rotational speed control, and for reading desired information by moving the information reading device from the disk. The point is that it allows access.

Another feature is that a disk motor rotation speed detector is provided, and the rotation speed detected by the disk motor rotation speed detector is compared with the predicted rotation speed, so that the former is equal to the latter. The point is that the rotation speed is controlled so that the

(Example) FIG. 7 shows an example of the present invention. 7 (in ζ, the same symbols as in FIG. 1 indicate the same functions. 24 is a target voltage output circuit, an example of which is shown in FIG. 8).

The target voltage output circuit shown in FIG. 8 is composed of a plurality of precented voltage sources and a changeover switch 25. The target voltage output circuit shown in FIG. Switch 25 is controlled by system control circuit 23. The system control circuit 23 has a built-in table as shown in Table 1 below, and selects the target rotation speed according to the absolute time of the random access target position. This voltage corresponding to the rotational speed ζ is the preset voltage source shown in FIG. 8, and by switching the switch 25, a motor drive voltage close to the rotational speed at the target position is supplied to the motor 2.

Table 1, Figure 9 shows the access situation. In this embodiment, after setting the voltage to reach the target rotation speed prior to access,
(The pressure on the motor drive 7 is indicated by a broken line).Access is performed. Once the access is complete, the engine changes from startup mode to steady mode.The difference from Figure 5 is that the rotation speed is very close to the target rotation speed when it enters startup mode. .

Therefore, the time 1'2 required to enter the steady mode can be made shorter than T1. Furthermore, if the number of voltage sources shown in FIG. 8 is increased and the error from the target rotational speed is within ±5%, it is possible to make T2 almost O.

The target voltage output circuit 24 may be configured with a PWM wave generator using a well-known clock and counter.

FIG. 10 shows an example. 26 is a counter that is set at the reference frequency and has a preset value set according to the absolute time of the random access target position. Further, 19 is the LPF shown in FIG.

Since the counter 26 is set at the reference frequency, it outputs a signal of a constant frequency to the LPF 19. However, since the duty of the rectangular wave output from the counter 26 changes depending on the preset value, the voltage output from the LPF 19 can be multiplied by a value l corresponding to the target rotation speed at the random access target position.

FIG. 11 shows a flowchart of a characteristic part of the function of the system control circuit 23 of FIG. 7, and shows a step in place of step S4 between point A and point B in the flowchart of FIG. That is, in FIG. 6i (in step S4
The function of the system control circuit 23 in FIG. 7 is replaced by steps 820 to S22 in FIG. 11.

Among the functions of the system control circuit 23, steps 81 to S3 and steps 85 to S17 are the sixth
This is the same as the conventional example shown in the figure. Therefore, only steps 520-822 shown in FIG. 11 will be described.

Step 820...The number of rotations of the disk for 16 minutes 00 seconds read from the RAM in step S2 is RO
Read from M. From this, it can be determined that, for example, there are 5 or 6 rotations.

Step S21...The motor voltage required for 5 and 6 rotations is determined by reading the data stored in RO and M.

For example, it can be seen that it is 1.6V.

Step S22: Depending on the selection of the selector switch 25 in FIG.

FIG. 12 shows another embodiment of the invention. In Figure 1C,
30 indicates a motor rotation speed detector, and other symbols indicate the seventh
Indicates the same thing or equivalent as in the figure.

In the apparatus shown in FIG. 7, if the voltage-rotational speed characteristic of the disk motor varies or if the voltage-rotational speed characteristic changes due to disk load characteristics, an error fζ may occur with respect to the target rotational speed.

In this embodiment shown in FIG. 12, in order to absorb this error, after inputting information to the target voltage output circuit 24, the output of the rotation speed detector 30 is compared with the predicted target rotation speed,
Furthermore, correction data is sent to the target voltage output circuit 24i to bring the motor rotational speed closer to the target rotational speed.

FIG. 13 shows a target voltage output circuit 24 suitable for this embodiment.
An example is shown below. Further, FIG. 14 is a waveform diagram for explaining the operation of the circuit of FIG. 13.

In FIG. 13, 101 and 102 are constant current sources, 10'
3, 104, 105 are switches controlled to be turned on and off by the system control circuit 23; 106 is a capacitor; 107 is an operational amplifier;
9 indicates a motor. Capacity 106 and operational amplifier 107
An integrating amplifier consisting of an integral amplifier and two positive and negative constant current sources 101.10
2 constitutes a ramp function generator.

The data detected by the rotation speed detector 30 in FIG. 12 and the predicted target rotation speed data are compared in the system control circuit 23. Then, when the rotation speed of the motor 109 or 2 is smaller than the target rotation speed, the system control circuit 23 turns on the switch 104. Then, the output of the ramp function generator, ie, the output of the operational amplifier 107, increases as shown in FIG. This also increases the rotational speed of the motor 109. Then, when the rotation speed of the motor 109 or 2 detected by the rotation detector 30 becomes equal to the target rotation speed, the switch 104 is turned off by the system control circuit 23.

As a result, the output of the operational amplifier 107 is held at a constant value.

Conversely, the motor 109 or 2 detected by the rotation detector 30
When the rotation speed is higher than the target rotation speed, switch 10
3 is turned on. Note that the switch 105 is for resent.

FIG. 15 shows the system control circuit 23 of FIG.
FIG. 6 shows a flowchart of the characteristic part of the function of FIG. That is, in FIG. 6, steps 830 to 8 in FIG. 15 are performed instead of steps S4 and 85.
43 to 72 represents the function of the system control circuit 23 shown in FIG.

Among the functions of the system control circuit 23, steps 81 to S3 and steps 86 to S17 are the same as in the conventional example shown in FIG. Therefore, only steps 530-843 shown in FIG. 15 will be described.

Step S30: The number of rotations of the disk for the absolute time of 16 minutes 00 seconds read from the RAM in step S2 is read from the ROM.

From this ζζ, it can be seen that there are 56 rotations.

Step S31...Turn off the track servo.

Step 832...X seconds determined in step S3 is input to the timer in the system control circuit.

Step 833: The pickup is moved.

Step 834...Change the voltage of motor 2 and
change the rotation speed of the motor.

Step S35: It is determined whether the number of rotations of the motor 2 is 56 rotations. If no, the process advances to step S36; if yes, the process advances to step S37.

Step 336: If no, it is determined whether the timer has reached zero. Note that the timer is decremented every second by the interrupt program. If YES in step S36, the process advances to step S39. If step S36 is YES, the motor rotation speed is 56.
It is clear that this means that X seconds have come before the rotation.

Step 837: When the motor rotation speed reaches 56 rotations fζ before the X seconds, the process proceeds to step S37 and the motor voltage is fixed.

Step S38: It is determined whether or not the timer has reached O, and when X seconds have passed, the process proceeds to step S39.

Step 339: Stop the movement of the pickup.

Step 840...Turn on the track servo.

Step S41: It is determined whether the motor rotation speed is 56 rotations. If no, the process proceeds to step S42; if yes, the process proceeds to step S843.

Step S42: Change the motor voltage.

Step S43: Fix the motor voltage.

The reason why steps 341 to 343 are provided is that when the process advances to step S39 through steps 834 to S36, the motor voltage has not been fixed yet, so the motor voltage is fixed in steps 841 to S43. This is to fix the On the other hand, step S34. S35,8
37, 838 to step 839, the motor voltage has already been fixed in step 837, and the fixing of the motor voltage in step S43 is redundant, but there is no operational difference. There is no problem.

Further, FIG. 16 shows still another embodiment of the present invention. 31
is the position detector of the information reading device. For CD type discs, the recording linear velocity is 1.2 m/s to 1.4 m/s
and may vary depending on the disc. Linear speed is 1.2
m/B disk has an error with respect to the target rotation speed predicted by the absolute time-rotation speed correspondence table calculated at 1.4 rn/s.

Therefore, if the information reading device position detector 31 detects the disk radius R at the reading position and the rotation speed detector 30 detects the rotation speed f, the linear velocity V can be calculated as v=2πR−f.

Therefore, if several kinds of absolute time-rotation speed correspondence tables are prepared in advance in the memory of the system control circuit 23 according to the linear velocity, and the correspondence table corresponding to the calculated linear velocity is selected, predictions based on changes in linear velocity can be made. The error in rotation speed can be reduced.

(Effects) According to the present invention, as described above, the time required for the disk motor to reach steady rotation after random access is significantly shortened, so there is an effect that the time required for random access can be shortened.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventionally proposed signal reproduction speed control system, Fig. 2 is a waveform diagram showing the structure of a modulated signal, Fig. 3 is a diagram showing the switching state of the switch in Fig. 1, and Fig. 4 is a diagram showing the relationship between disk radius and rotation speed, Figure 5 is a diagram showing the motor servo mode and motor rotation speed at the time of access, and Figure 6 is a diagram showing the relationship between disk radius and rotation speed.
7 is a block diagram showing an embodiment of the present invention, FIG. 8 is a circuit diagram of the target voltage output circuit, and FIG. 9 is a flowchart explaining the functions of the system control circuit of FIG. 1. Diagram showing motor rotation speed during access, No. 10
Figure 11 is a block diagram of another specific example of the target voltage output circuit, Figure 11 is a flowchart showing the functional features of the system control circuit of Figure 7, and Figure 12 is a block diagram of another embodiment of the present invention. , FIG. 13 is a block diagram of another specific example of the target voltage output circuit, FIG. 14 is a waveform diagram for explaining the operation of the circuit in FIG. 13, and FIG. 15 is a function of the system control circuit in FIG. 12. FIG. 16 is a block diagram of still another embodiment of the present invention. 1...Digital audio disc, 2...
Motor, 3... Synchronous signal detection circuit, 5... Pseudo synchronous signal generation circuit, 6... Frequency voltage converter (F
-■Converter) 7.19...low-pass filter, 8...
・Error amplifier, 11... Discriminator, 15 ・Reference frequency oscillator, 16.17... Frequency divider, 18...
Phase comparator, 20... Hold circuit, 23...
System control circuit, 24...Target voltage output circuit, 30...Rotation speed detector, 31...Position detector of information reading device Patent attorney Michito Hiraki 3'1 Figure 2 Figure 3 Figure off Figure 2'8 Figure 'A'9 Figure

Claims (6)

[Claims] (1) Equipped with a synchronization signal detection and regeneration circuit and a pseudo synchronization signal generation circuit that predicts and generates the synchronization signal period from a specific pulse width, and within the synchronization signal detectable range, the output of the synchronization signal detection and regeneration circuit, and the synchronization signal detection range Means and prediction for predicting the number of rotations of a disk at a target position of random access in a reproduction speed control device for a disk in which an information signal and a synchronization signal for speed control are recorded by switching to the output of the pseudo synchronization signal generation circuit. and a means for moving the information reading device at the same time as or after performing the rotation speed control, and moving the information reading device that reads information signals from the disk to obtain desired information. 1. A playback speed control device for an information recording disk, characterized in that the device performs random access for reading information. (2) The rotation speed at the target position is predicted based on the absolute time-rotation speed correspondence table recorded in the storage device, and the rotation speed is controlled by selecting a voltage source according to the prepared rotation speed. A patented disc playback speed control device characterized in that it performs the following functions. (3) Prediction of the rotation speed at the target position is performed using an absolute time-rotation speed correspondence table recorded in a storage device, and the rotation speed control is performed using a PWM wave generator and a reduced P wave generator connected in series. 2. A playback speed control device for an information recording disc according to claim 1, characterized in that: (4) Equipped with a synchronization signal detection and regeneration circuit and a pseudo synchronization signal generation circuit that predicts and generates a synchronization signal period from a specific pulse width, and within the synchronization signal detectable range, the synchronization signal detection and regeneration circuit outputs, In a disc playback speed control device in which an information signal and a synchronization signal for speed control are recorded by switching to the output of the pseudo synchronization signal generation circuit, a disc motor rotation speed detector/random access target position is detected. means for predicting a disk rotation speed; means for comparing the rotation speed detected by the disk motor rotation speed detector with the predicted rotation speed and controlling the rotation speed so that the former becomes equal to the latter; The present invention is equipped with a means for moving the information reading device at the same time as controlling the rotation speed or after controlling the rotation speed, and by moving the information reading device that reads information signals from the disk, random access is performed to read desired information. Features: A playback speed control device for information recording discs. (5) The playback speed of the information recording disk described in item 4 of the patent encirclement, wherein the means for controlling the rotational speed includes an integral amplifier and a Lang function generator made up of two constant current sources with different polarities. Control device. (6) An information reading device position detector is provided, and the disc recording linear velocity is detected by the output of the position detector and the output of the disc motor rotation speed detector, and absolute time versus rotation speed is calculated according to the linear velocity. The fourth aspect of the present invention is characterized in that the number of revolutions at the target position is predicted based on the calculation or the storage device (cod selection) that records the calculation results.
6. A playback speed control device for an information recording disc according to item 1 or 5.